The present invention relates to a method and apparatus for detecting disconnection of an oxygen sensor, and more particularly, a method and apparatus for diagnosing disconnection of an oxygen sensor, which is capable of measuring a voltage and internal resistance of the oxygen sensor and determining whether a ground wire of the oxygen sensor is disconnected, based on the measured values.
Recently, due to the acceleration of environmental pollution, restrictions on exhaust gas having a large influence on air pollution have been strengthened in the automobile industry.
Each country forces automobile manufacturers to reduce exhaust gas through various regulations.
So far, a method has been developed and widely used to reduce exhaust gas of a vehicle. According to the method, a catalytic converter is attached to an exhaust pipe so as to filter harmful gas contained in exhaust gas, or the concentration of oxygen contained in exhaust gas is measured through an oxygen sensor in order to burn fuel at an optimal air-fuel ratio.
That is, based on the oxygen concentration of the exhaust gas, sensed through the oxygen sensor, the amount of air required for burning fuel is fed back to adjust a fuel injection amount at the optimal air-fuel ratio at which the smallest amount of harmful gas is discharged.
The related art of the present invention is disclosed in Korean Patent Laid-open Publication No. 2012-0124691 published on Nov. 14, 2012 and entitled “Method for diagnosing oxygen sensor of vehicle”.
When the oxygen sensor breaks down, the oxygen sensor cannot precisely measure the oxygen concentration of exhaust gas. Thus, much attention is being paid to a technology for diagnosing a failure of an oxygen sensor.
That is, when a disconnection or short fail occurs in the oxygen sensor such that the oxygen sensor does not perform a normal operation, the air-fuel ratio cannot be controlled because the oxygen sensor cannot determine whether the current air-fuel ratio is higher or lower than a theoretical air-fuel ratio.
Furthermore, since the amount of harmful gas contained in the exhaust gas may increase in a state where the air-fuel ratio cannot be controlled, there is an increasing need for a technology capable of precisely determining whether an oxygen sensor is normally operated.
According to the recent trend, monitoring parts related to exhaust gas of a vehicle and diagnosing a failure through OBD (On Board Diagnosis) have been mandatory.